The use of portable terminals has increased due to their portability. Thus, terminal manufacturers have competitively developed portable terminals with more convenient functions in order to attract more users. For example, portable terminals now typically provide various functions such as phone books, games, schedulers, short message services, multimedia message services, Internet service, e-mail service, wake-up calling, MPEG Audio Layer-3 (MP3) players, and digital cameras.
In order to provide portability, portable terminals typically use a detachable rechargeable battery as a power supply. Due to a limited capacity of the rechargeable battery, users of the portable terminal are often required to check a rechargeable battery level and charge the rechargeable battery by using an external power supply.
The portable terminals display a battery level indication bar on its display screen so that users can easily recognize a current battery level. The battery level indication bar includes a plurality of bars, and the number of bars gradually decreases with an increase in battery consumption to inform the user of the time when the rechargeable battery is completely consumed.
In general, a portable terminal has a battery gauge to monitor a battery level.
When a battery gauge is used, a battery level can be exactly detected. However, the battery gauge and a circuit for operating the battery gauge causes an increase in the unit price of a portable terminal.
In order to overcome the above problem, a portable terminal estimates a battery level by measuring a battery output voltage, instead of by use of a battery gauge. That is, the portable terminal estimates a battery level by predefining and prestoring a battery level for each battery output voltage in a battery voltage table and measuring an output voltage. Although this technique may be less expensive, when the battery output voltage is used, the accuracy may be low compared to using the battery gauge. Nevertheless, when an application with relatively high current consumption is executed in a portable terminal, a voltage across a battery drops due to this increase in current consumption. As a result, when a battery level is estimated using a battery output voltage, a battery level lower than a current battery level is estimated.
Therefore, there is a need for an apparatus and method for improving the performance of a battery level estimation using a battery output voltage in a portable terminal.